I have multiple Private IPs assigned to my Marketing Cloud account. Learn which one is used when the delivery profile is set to "default."

Resolution

The multiple IPs will work as a Private Shared pool of IPs by default, unless specifically configured otherwise. The system will send round-robin Sends from those IPs in batches of 500, depending on the content of the email. If the account is setup this way, it'll follow the standard procedure for sending once the messages hit the OMM for building.

Ideally, a different delivery profile for each IP should be configured by an Admin of the Marketing Cloud account, and the appropriate profile will be used when sending.